Developments in technology have changed the way information is displayed and communicated to groups of people. Traditionally chalkboards and whiteboards have been used for these purposes. However, chalkboards and whiteboards have significant drawbacks. First, they cannot be easily integrated with electronic information displays. Second, they require specialized writing surfaces that are compatible with chalk, dry erase markers, or similar writing tools. Third, information written on these types of surfaces is not easily captured electronically for computerized processing or display. While some whiteboards have electronic scanning capability, electronic scanning can be costly for large whiteboards as the scanning mechanism(s) must typically span the entire whiteboard or span an entire dimension of the whiteboard and be configured for controlled mechanical movement across the other dimension of the whiteboard.
Written information is also often electronically captured using an electronic touchpad that translates motion of a stylus, a user's finger, or another pointing device into electronic information. The information is typically captured relative to a position of the stylus, pointer, or finger on a surface or on a display screen. Touchpads are commonly integrated with or overlaid on a display screen, such as on a smartphone or tablet computer. Touchpads are also sometimes implemented in or on non-display surfaces such as on a digitizing tablet for computerized drafting system. A touchpad typically allows information to be electronically captured more efficiently than other methods as the user is not required to enter the information using a traditional input device such as a keyboard or a mouse. In addition, a touchpad enables the user to provide freehand or freeform written input.
Touchpads typically sense a user's actions using one of several methods including capacitive sensing, conductance sensing, and/or using a pressure sensitive membrane. Each of these methods requires that the display surface be overlaid with electrical and/or mechanical hardware which enables the surface to become touch sensitive. The cost of adding touch sensing capability to displays increases proportionally, and in some cases exponentially, with the increasing area of the screen. In some situations, the cost increases even further due to manufacturing yield issues associated with large areas. Consequently, touch input capabilities can be prohibitively expensive as display sizes increase. For this and other reasons, large numbers of displays are sold without touch input capability. It is desirable to add touch input capabilities to these displays in a cost effective manner. In addition, it may be desirable for a user to be able to provide written input using a stylus or finger on a surface other than on a surface of a display.